Hey Guys -

First time Rover owner here (2000 Disco II). Fortunately I have quite a bit of experience working on cars and motorbikes. Anyway, I bought the Disco several weeks ago and have been sorting out some issues with the help of this forum. So far I have fixed the cruise control (easy), and thought I had gotten rid of all the trouble codes, however 2 codes (p1171 and p1174 - lean running on bank 1 and bank 2) keep coming back.

Here is what I have done so far: replaced front o2 sensors, replaced MAF sensor, cleaned air filter, checked fuel pressure, ran fuel injector cleaner, checked for intake air leaks using carb cleaner spray. Any other ideas? I should note that one of the wire clasps is broken on the intake air box, could this cause the problem?

Regards,

Brian

 

If you are absolutely sure you don't have any air leaks, your flow meter has crapped out.

 

Thanks priceg, guess I will double-check for intake leaks. Let you know what I find...

 

Just did a ghetto smoke test (using a cigar) and didn't find anything as far as leaks. Can I say with certainty that it's a problem with the MAF?

Thanks

 

The broken clasp would impact dirt intake, but vac leaks that cause problems need to be past the MAF sensor (un-metered air). Don't forget the PCV vent system as well. You can use MAF cleaner, but only do it when engine is stone cold, don't turn on ignition before spraying it, etc. When you power up sensors on the truck, the MAF heats a tiny place inside to about 430F. Spray cold liquid on that and bad things happen quickly due to thermal shock.

 

Who's MAF did you install, was it a Bosch with matching part numbers on the barrel or a generic Bosch or after market> Neither of those will work on your truck.

 

Disco Mike, it is a Bosch MAF sensor from a parted-out truck. I am going to torque down the intake manifold bolts, reset the codes, and see what happens. I'll report back...

BWB

 

So --- The 2 lean running codes came back (1174 and 1171). This evening I did another smoke test, and noticed some smoke coming from just behind the AC compressor underneath the intake manifold. Would this likely be an intake gasket leak?

Thanks


Brian

 

The valley pan gasket is infamous for having bolts that are finger tight.... see attached. BTW if you have to take off the top of the intake plenum, great time for plug wires and quick pressure test of fuel pump on test valve at rear of assembly.

Valve cover gaskets also leak if not snugged up with 8mm 12 point 1/4 inch socket. PCV system circulates thru them by plenum vacuum. Clean out item 9 on attached with carb cleaner.

 

I was getting the same codes with broken airbox clips. I replaced the airbox, replaced all the vacuum hose clamps with screw type clamps and cleaned the oil seperator in the valve cover vacuum hose connection. Still got the codes so I replaced the MAF with one from here.

Make sure the airbox is fixed before replacing the MAF otherwise it will just get dirty again. Mine had a bug sticking to the MAF screen so I'm pretty sure the broken air box is what killed the MAF.